This invention relates to an apparatus for measuring the minimum pressure applied to a patient which elicits discomfort, for example the pressure applied to a joint of an arthritic patient.
Physicians place an important role on patterns of pain in the diagnosis and management of their patients. Manual palpitation is the standard method of examination, but it has a certain drawback, namely that the procedure is subjective and lacks the precision necessary to accurately assess, for example, the degree of inflammation of arthritic patients.
The limitations of manual palpitation have been addressed by providing mechanical devices known as dolorimeters, algesimeters or algometers (the terms are used synonymously herein). In the simplest form, a mechanical dolorimeter includes a simple spring loaded probe connected to a gauge. The gauge indicates the deflection of the probe and hence the pressure applied to the probe. In use, the physician presses the probe against the inflamed joint or other portion of the patient's body suffering pain, and applies pressure until the patient feels discomfort. The reading of the gauge is noted, the reading being an objective indication of the degree of inflammation of the joint, for example.
Electronic dolorimeters have been developed, such as disclosed in U.S. Pat. No. 4,641,661 to Kalarickal. This device includes an electronic circuit housed in a hand-held unit. The dolorimeter has a probe with a resistance which varies according to pressure applied to the probe. The hand-held unit is capable of measuring the resistance of the probe and thereby the pressure applied.
Other devices for determining or recording the pain sensitivity or the like are disclosed in U.S. Pat. No. 4,501,148 to Nicholas, U.S.S.R. Patent No. 166,999, Federal German Patent No. 230,696 and European Patent No. 158,336 to Wood.
All of the devices described above substitute the finger of the physician with an inanimate probe. For this reason, they have an inherent drawback in that they remove certain advantages to the physician and the patient inherent in the touch of the physician's finger. The physician's finger is capable of determining with accuracy the precise point where the pain threshold is to be assessed. It is not always easy for the physician to press the inanimate probe at precisely the right location because he or she receives no direct tactile feedback from the probe. In addition, there is an impersonal aspect objectionable to some patients associated with the act of being pressed with an inanimate object. Many patients would prefer the more personal contact of a physician's finger.
It is therefore an object of the invention to provide a dolorimeter apparatus which can output a objective reading of the minimum pressure which causes discomfort and the beneficial aspects of manual palpitation.